Self-locking nut



Oct. 5, 1948. J. A. SAUER 2,450,694

SELF-LOCKING NUT Filed Jan. 21, 1944 IN V TOR X4 2242;

M/VW

Patented Oct. 5, 1948 OFFICE SELF-LOCKING NUT- John A. Sauer, Elizabeth, N. J., assignor .to Elastie Stop Nut Corporation of America, Union,

N. J., a corporation of New Jersey Application January 21, 1944, Serial No. 519,135

7 5 Claims. (01. 151-7) The present invention threaded fastening devices and hasparticular reference to self-locking nuts. More specifically the invention relates to such devices in which the locking action is obtained by the provision of abody of elastic locking material located so that a thread is impressed therein, in the case of a.

nut, by the thread of the cooperating bolt. Nuts relates to self-locking 4 of the nut upon repeated re-use of the of this character are disclosed in the Rennerfelt;

Patent No. 1,550,282, granted August 18, 1925, and Swanstrom Patent No. 2,153,681, granted April 11, 1939.

For the purpose of illustrating the present invention, but without limitation, the accompanying drawing shows a typical nut of the character under consideration, the device comprising a body In, ordinarily of metal, having a, threaded bore portion l2 at one end of which is an annular recess H filled by a locking collar I 6 of elastic non-metallic material. The bore I 8 of the collar I6 is somewhat smaller than the' major diameter of the thread [2, screwed On a bolt, the bolt thread impresses a thread in the collar, the latter being confined, when the nut is applied, between the walls of the recess on the one hand and the threaded wall of the bolt on the other hand. The principal material heretofore commercially employed for such locking collars has been vulcanized fiber. While vulcanized fiber has proved the best material heretofore known for this purpose, it has certain quite well recognized deficiencies. Vulcanized fiber is not waterproof but will absorbmore than 50% of its weight of water upon continued immersion, causing the fiber to swell and then shrink again upon drying out. If a nut becomes wet before application to a bolt. the fiber collar has a tendency to be pushed out of place by the bolt, and if it becomes wet and then dry, the collar has a tendency to shrink and become loose and turn in its seat. Fiber does not have as good elastic recovery or spring-back as might be desired after the nut has been removed and as a consequence the nuts cannot be effectively re-used more than a limited number of times. It is found that if a self-locking nuthaving a fiber collar is taken off and then screwed on to'the bolt a second time the frictional locking resistance to removal is appreciably lower than the locking resistance offered by the initial application.

-An ideal elastic locking collar for this type of self-locking nut should have the following characteristics: 1) no or very low water absorption; (2) good dimensional stability llndcfivarving con so that when the nut is temperature range in which ditions of temperature and humidity; (3) good elastic recovery so that there is no appreciable reduction in the frictional grip against removal nut; (4) the surin contact deleterious within the the nuts are emresistance to shredding or chipping 'of face of the material when it is turned with the screw threads; and (5) no effects by changes in temperatures ployed.

I have found materials which are unique and peculiarly adaptable for making such locking collarsand which possess to a very high degree the} above enumerated properties of an ideal locking material. Such'materials are ofthat class of superpolymeric condensation products of polyamines and polybasic. acids derived from diamines and dibasic acids of which hexamethylene diamine and adipic acidare the preferred materials. In order tosecure the desired results from the present invention, the synthetic linear superpolymers of such materials, s'uch'as aredisclosed in the Carothers Patent No. 2,130,948 of September 30, 1938, and'of which nylon is a commercial example, are used, and'as herein employed the terms defining the material are to be considered in the sense as used and defined in said Carothers patent.

A locking collar of such material has good dimensional stability under varying conditions of humidity. Its water absorptivity is low, having a a maximum of about 7 percent. under continued immersion. It has an excellentelas'tic recovery orspring-back so that there is noappreciable drop in the torsional resistance to removal of the nut even after as many as or re-applications of the nut. It is remarkably tough and shows no appreciable shredding or chipping of the surface as a result of its application to the screw threads. not deleteriously affected by temperatures from -'75 F. up to that of 212 E, which covers the temperature range encountered by most lock nut applications. I

Self-locking nuts in which my improved lockingcollars have been substituted for the usual fiber locking collars therefore retain their locking characteristics much better under humid conditions and can be' re-used practically indefi nitely, as contrasted with the limited reuse of lock nutshaving the fiber collars. My locking collars are also lessaffected by temperatures than those of the usual vulcanized fiber. 'An appreciable economy in the manufacture of the collars can be effected since nylon'is ther- Its locking characteristics are "3 moplastic under high and the scrap material can be re-worked. Y

While I have described the preferred embodiment of my invention, it is to be understood that the invention is not so limited but may be otherwise embodied within the scope of the following claims. a

I claim: I

1. A threaded fastening device comprising means providing a threaded portion for engagement with a threaded element havin a complementary thread, means providing a recess in said device for locking material and a body of'locking material comprising a synthetic linear superpolymer of a diamine and a dibasic acid in said recess, said body including a portion projecting laterally relative to the axis of said threaded portion past the root diameter of the thread thereof to provide a surface located to be traversed and engaged by said complementary thread to cause 20 displacement of said locking material due to the impression of a thread therein by said complementary thread when said device and element are threaded together, said body of locking material being substantially confined between the walls of 25 said recess and the thread of the element causing said displacement, whereby to create and maintain compressive pressure within said body of locking material to cause the; same to grip said complementary thread due to said pressure.

2. A device as set forth in claim 1 in which said body of locking material comprises a superpolymeric condensation product of hexamethylene diamine and adipic acid.

3. A device as set forth in claim 1 in which said body of locking material comprises a synthetic linear superpolymer of a diamine and an acid of the dicarboxylic group.

4. A device as set forth in claim 1 in which said device is provided with a threaded bore for engagement with an element having a complementary external thread.

5. A device as setforth in claim 4 in which,

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,550,282 Rennerfelt Aug. 18, 1925 2,286,336 Brooke June 16, 1942 2,286,668 Brooke June 16. 1942 

